Interface to fes control system

ABSTRACT

A functional electrical stimulation system ( 30 ) for controlling the movement of a portion of a body of a subject ( 12 ), such as the subject&#39;s legs. The system ( 30 ) comprises a sensor ( 60 ) that in one arrangement is mountable to a portion of the subjects&#39; body other than the legs, for example the torso ( 14 ). In another arrangement, the sensor ( 60 ) can be mountable to a walking aid, such as a crutch ( 20 ). The sensor ( 60 ) outputs signals representative of the position and/or movement of the torso ( 14 ) or walking aid ( 20 ). The system ( 30 ) also comprises a control means ( 32 ) that receives and processes the signals output by the sensor ( 60 ) and outputs control signals to a stimulator ( 35 ) adapted to provide electrical stimulation to the legs via electrodes ( 53 ) in response to the position and/or movement of the torso ( 14 ) or walking aid ( 20 ) as determined by the sensor ( 60 ).

FIELD OF THE INVENTION

[0001] The present invention relates to a functional electricalstimulation (FES) system and method of using such a system. Moreparticularly, the invention relates to a device and method for providinga person using functional electrical stimulation with a means ofcontrolling the electrical stimulation provided to their limbs.

BACKGROUND OF THE INVENTION

[0002] In the area of medical technology, much advancement have beenmade to assist individuals who have previously been considered to bedisabled in some way, to lead a relatively normal life in spite of suchdisabilities. Such advancements include the provision of hearing aidsand cochlear implants for the hearing impaired, as well as pacemakersfor those who experience cardiac problems, to name a few. However withregard to persons suffering from spinal cord injury and those who havelost function of their limbs, the provision of a device or devices toreturn desired function to the individual has as yet proven difficult toimplement. Functional electrical stimulation (FES) systems of varioustypes are seen to have particular application in providing personssuffering from spinal cord injury or deficiency, such as paraplegia,with a capacity to make controlled movements of their dysfunctionallegs.

[0003] Functional electrical stimulation systems use electronics togenerate electrical impulses. These impulses are then delivered to thenerves or muscles of a subject via electrodes to stimulate movement ofthe muscles that are otherwise dysfunctional. In order for useful andcontrolled movements of limbs to be achieved several muscles mustusually be operated in concert. This is normally achieved by analgorithm executed under the control of the FES system to deliver apattern or sequence of stimulation impulses.

[0004] An important aspect of the successful implementation of such anFES system is the provision of a control technique that controls thelimbs of a patient so that they follow a desired trajectory. It isextremely difficult, however, to choose a trajectory of the limbs sothat a functional task such as standing is performed. In one proposal,control is provided by a touch pad interface which can be activated bythe subject's fingers to some control types of movement, such asstanding, sitting and walking.

[0005] Such touch pad interfaces as known in the art do not provide anintuitive interface for the subject with the FES system and assume thatthe subject has full hand control to enable use of such a device.Existing FES systems are, therefore, relatively difficult to learn howto use and require a certain amount of dexterity which has the potentialto move subjects in undesirable ways.

[0006] Any discussion of documents, acts, materials, devices, articlesor the like which has been included in the present specification issolely for the purpose of providing a context for the present invention.It is not to be taken as an admission that any or all of these mattersform part of the prior art base or were common general knowledge in thefield relevant to the present invention before the priority date of eachclaim of this application.

SUMMARY OF THE INVENTION

[0007] Throughout this specification the word “comprise”, or variationssuch as “comprises” or “comprising”, will be understood to imply theinclusion of a stated element, integer or step, or group of elements,integers or steps, but not the exclusion of anti other element, integeror step, or group of elements, integers or steps.

[0008] According to a first aspect, the present invention is afunctional electrical stimulation system for controlling the movement ofa portion of a body of a subject comprising:

[0009] a measuring means having at least one sensor, mountable to aportion of the subject's body other said body portion, that outputssignals representative of the position and/or movement of said otherportion of the subject's body; and

[0010] a control means that receives and processes the signals output bythe measuring means and outputs control signals to a stimulating meansadapted to provide electrical stimulation to said body portion inresponse to the position and/or movement of said other body portiondetermined by the measuring means.

[0011] In one embodiment of this aspect, the said other body portion isselected from the group comprising the torso, the head or one or bothalms of the subject.

[0012] In a further embodiment, said body portion is one or both legs ofthe subject.

[0013] The present invention provides a system that can be relativelyeasily used, in one arrangement, to generate one or more desired anglesbetween the respective thighs and lower legs of a paraplegic with thelegs being controlled by electrical stimulation of the muscles so thatthe actual measured angle of the thigh and lower leg corresponds to thedesired angles.

[0014] In a preferred embodiment, the measuring means measures the angleof the subjects torso relative to a predetermined plane. Thepredetermined plane can be a sagittal plane, a frontal plane or ahorizontal plane. In one embodiment, the measuring means only measuresthe angle when the torso has stopped gross movement. In anotherembodiment, the measuring means measures the angle throughout the rangeof movement of the torso.

[0015] In another embodiment, the measuring means detects torsomovements that are determined by the control means as indicative thatthe subject wishes to roll over when they are in a horizontal position,such as when they are asleep. Such torso movements will typicallycomprise twisting movements of the torso.

[0016] In yet another embodiment, the measuring means measures the angleof the torso relative to the position of one or both of the lower limbsof the subject.

[0017] In one embodiment, the measuring means can be carried by thesubject. The measuring means may be carried in a harness or clothingworn by the subject. In another embodiment, the measuring means may bestrapped about the torso of the subject. In an alternative embodiment,the measuring means or componentry thereof can be implantable within thesubject.

[0018] In a preferred embodiment, the measuring means comprises one ormore transducers that outputs signals representative of the positionand/or movement of the transducer to the control means. Where themeasuring means is measuring the angle of the torso relative to thelower limbs, a transducer can be mounted on the torso and on one or bothof the lower limbs. More than one transducer mounted on the torso and/orthe lower limbs can be envisaged. Each of the transducers in this casewould output signals to the control means.

[0019] The control means preferably processes the output signals of thetransducer or transducers and then outputs signals to the stimulatingmeans to provide electrical stimulation to the muscles of the subject.The control means can execute an algorithm that leads to provision ofelectrical stimulation to the appropriate muscle(s) at the appropriateintensity as dictated by the subject or a predetermined programme. Theoutput signals of the transducer or transducers and those of the controlmeans to the stimulating means can comprise electrical or opticalsignals.

[0020] In a further embodiment, the control means can have a storagemeans having at least one predetermined action sequence storabletherein. On receipt of signals from the measuring means, said at leastone predetermined action sequence can be provided to the stimulatingmeans. The predetermined action sequence can result in the subjectmoving from a standing to a sitting position, or moving from a sittingto a standing position, walking, or moving the legs in a pedallingaction. Other suitable predetermined action sequences can be envisaged.

[0021] In one embodiment, the control means is adapted to output apredetermined sequence of signals to the stimulating means uponreceiving signals from the transducer or transducers that the subject'storso is at a particular pre-determined angle relative to a plane, suchas a notional horizontal plane, or the lower limbs. For example, whenthe subject bends their torso forward from the hip this can be measuredby the transducer with appropriate signals provided to the controlmeans.

[0022] In one embodiment, the pre-determined sequence of signals to thestimulating means can be output by the control means when the torso hasbent forward by an angle of between about 10° and about 60°, morepreferably between about 25° and 50°, and still more preferably betweenabout 25° and 45°.

[0023] In another embodiment, the control means is adapted to output aseries of pre-determined signals representative of the position of thesubject's torso. A particular series of various positions of the torsocan cause the control means to output a particular series of signals tothe stimulating means so causing a particular series of stimulations tothe muscles of the subject. This allows a subject to learn a particularseries of movements that lead to a particular desired series ofmovements of the stimulated limbs of the subject. For example, amovement or series of movements of the torso may initiate a step by aleg or a series of steps by the subject's legs. Alternatively, amovement or a series of movements of the torso may initiate ate astanding or sitting action.

[0024] In response to the detection of signals from the control means,the stimulating means is adapted to output electrical impulses. Theseimpulses are transmitted to the subjects nerves or muscles from astimulator through electrically conducting leads to stimulationelectrodes. The electrodes can be surface mounted on the skin of thesubject, percutaneous intramuscular electrodes that are implanted with aminimally invasive needle insertion procedure, or fully implantedelectrodes. The stimulating means preferably bas circuitry adapted todrive whatever electrodes are selected for use with a particularsubject.

[0025] In one embodiment, the stimulator can be carried by the subject.The stimulator can be carried in a harness or clothing worn by thesubject. In another embodiment, the stimulator may be strapped to thesubject. In an alternative embodiment, the stimulator or componentrythereof can be implanted within the subject. The electrical leadsextending from the stimulator to the electrodes can be totallyimplantable within the subject or carried externally on the body of thesubject.

[0026] In a preferred embodiment, the electrodes can be mounted to thelower limbs of the subject. It will be envisaged that the electrodescould be mounted to the upper limbs or that electrodes may be mounted toboth the upper and lower limbs of the subject.

[0027] Where the electrodes are mounted to the lower limbs, thepredetermined sequence of signals generated by the control means isprovided to the lower limbs.

[0028] In the embodiment where a bend of the torso to a pre-determinedangle relative to the horizontal plane is made, the control means can beprogrammed such that the predetermined sequence of signals generated ondetection of such a change in the position of the torso causes thesubject to be moved from a sitting position to a standing position orvice versa.

[0029] As discussed above, in another embodiment, a particular series ofvarious positions of the torso can cause the control means to output aparticular series of signals to the stimulating means so causing aparticular series of stimulations to the muscles of the subject. Forexample, when the subject is in a particular pre-determined position,the angle of the torso relative to the horizontal plane can determinethe angle between the thigh and lower leg of each leg of the subject.The control means preferably only allows torso movement to control limbangle when the subject is in a position that variation in limb angle isappropriate or safe for the subject. When the torso is upright, theangle between the torso and the horizontal plane is about 90°. If theangle between the thigh and lower leg is not about 90°, the stimulatingmeans stimulates the muscles within the leg until this angle isachieved. This should be relatively comfortable for the subject as whensitting upright in a chair a person's thighs are typically about normalto the lower leg. When the subject bends their torso relatively forward,the angle between the torso and the horizontal plane decreases. Thisdecrease in angle leads the control means to output signals causingflexion of the lower leg, preferably to a predetermined degree, somoving the feet to a position ready to allow the subject to stand. Oncethe feet se in position, the subject can, for example, move their torsobackwardly relative to the horizontal plane. This movement, if detectedby the control means following the previous forward movement, can leadthe control means to cause full extension of the legs so moving thesubject from a sitting to standing position.

[0030] Detection of other movements of the torso can lead the controlmeans to output other pre-programmed sequences of signals. For example,if the subject considers that they are not in a position to stand oncethe feet have been moved the predetermined degree, a her forward orother movement of the torso can cause the control means to stimulate thelower leg to return to a position about 90° relative to the thigh soleaving the subject in a sitting position.

[0031] When a subject is in a standing position, controlled movement ofthe torso can allow the subject to move to a sitting position. Forexample, forward bending of the torso relative to the horizontal plane(so decreasing the angle of the torso to the notional horizontal plane)can cause the control means to stimulate the legs of the subject todecrease the angle between the thigh and lower leg from about 180°gradually towards about 90° at which point the legs are in a position toallow the subject to comfortable sit upon a chair.

[0032] In another embodiment; when the subject is in a particularpredetermined position, variation in the angle of the torso and/or head,or both in combination, relative to the lower limbs can allow a subjectto control initiation of a step or sequence of steps. Sequentialvariations in torso position relative to the lower limbs can control aseries of alternate steps by the subject's legs. Preferably, the subjectcan learn to perform this sequential variation in torso and/or beadangle and so control their step movement. Again, the control meanspreferably only allows torso movement to control step initiation whenthe subject is in a position that step initiation is appropriate or safefor the subject.

[0033] A system of using torso and/or head angle allows the subject todefine their preferred limb angle. This allows the subject to be trainedto control the standing and sitting process or walking using the FESsystem. This gives the subject a greater sense of controlling thestimulation provided to their limbs rather than being in a position offeeling that the system is entirely in control of their movement. Thisis envisaged as providing the subject with a greater sense of confidencein using function electrical stimulation systems so leading to greateruse of the system.

[0034] As discussed above, the control means can be adapted to output apredetermined sequence of signals to the stimulating means on receivingsignals from the transducer that the subject is twisting their torso ina manner indicative that the subject wishes to roll over. In this case,the stimulating means can be adapted to stimulate the legs in a mannerthat assists the subject in turning over. In one embodiment, the systemwill assist turning over when the subject is asleep. In his case, it ispreferred that the stimulations to the legs are just sufficient toassist turnover without being of a magnitude that significantly disturbsthe sleep of the subject.

[0035] In a preferred embodiment, stimulation of the legs to assistturning over is only activated by the control means when the patient islying in a substantially horizontal plane. For example, the transducercan determine the orientation of the subject and provide a signal to thecontrol means representative of the orientation. In such instances,whenever the transducer is outputting a signal that indicates that thesubject is not substantially horizontal, the control means is lockedfrom outputting the signal sequence that would be employed to assistrolling over.

[0036] In another embodiment, the control means can be programmed tooutput signals to the stimulating means to cause roll over of thesubject at predetermined times or at predetermined rates. For example,the control means can be programmed to output signals causing roll overof the subject at least 2 times in an 8 hour period. These roll overscould be additional to those that occur in response to detection oftorso twisting or movement indicating a desire by the subject to rollover. In one embodiment, the control means could monitor the number ofassisted roll overs performed in response to torso movement or twistingand only institute an involuntary roll over if the subject has notrolled over for a predetermined minimum period of time. For example, thecontrol means may be adapted to institute an involuntary roll over if noroll over has occurred for at least 4 hours.

[0037] Assistance in rolling over provided by the present system shouldreduce the incidence of pressure sores and disrupted sleep for spinalcord injured persons who are unable to relieve pressure during sleep byrolling over.

[0038] In a preferred embodiment, the system includes a feedback meansthat measures the position and/or movement of said body portion beingstimulated by the stimulating means and provides output signals to thecontrol means representative of these measurements. The feedback meanscan comprise one or more transducers mounted to the limbs beingstimulated. Where a subject's legs are being stimulated, one or moretransducers may be mounted to the thigh and/or lower leg of the subject.In another embodiment, the transducers can be fully implantable withinthe legs.

[0039] The signals provided by the feedback means can be used tooverride the instruction provided by the subject by bending their saidother body portion, such as their torso, if the control means detectsthat the limbs are in an unsuitable position to be stimulated. Oncestimulation has commenced, for example to cause the subject to stand,the control means can also use the output signals of the feedback meansto determine if the limbs of the subject are responding and to adjustthe pattern and location of the stimulation if required. Such a feedbackmeans provides the system with the flexibility to adjust its performancedepending on the circumstances faced by the subject. For example, adifferent stimulation pattern may be required to successfully move asubject from a sitting position on a low couch to a standing positioncompared to that required to achieve the same result from sitting in anupright chair.

[0040] The signals provided by the feedback means can also be used bythe control means as a means of determining if the subject is in asubstantially horizontal position. If the feedback means outputs signalsto the control means that the subject is not substantially horizontal,the control means is preferably locked from outputting the sequence ofsignals that would normally be output to the stimulating means to assistrolling over on detection of torso movements normally indicative thatthe subject does wish to roll over.

[0041] In a preferred embodiment, the control means has an operatingmeans. The operating means preferably comprises an activation anddeactivation means. The activation and deactivation means preferablyallows the subject to turn on and off the control means and the FESsystem when desired. Where the FES system is fully implanted, theactivation and deactivation means is preferably controllable fromoutside the body. In one embodiment, the activation and deactivationmeans can comprise a switch. Where the control means is implanted, thesystem preferably can still be operated through the skin of the subject.The operating means preferably incorporates a locking means to preventinadvertent activation or deactivation.

[0042] Where implanted, an external controller can communicate with theimplanted unit using radio frequency (RF) transmissions.

[0043] According to a further aspect, the present invention is afunctional electrical stimulation system for controlling the movement ofa portion of a body of a subject comprising:

[0044] a measuring means having at least one sensor, mountable to awalking aid, that outputs signals representative of the position and/ormovement of said walking aid when operated by a subject of the system;and

[0045] a control means that receives and processes the signals output bythe measuring means and outputs control signals to a stimulating meansadapted to provide electrical stimulation to said body portion inresponse to the position and/or movement of said walking aid determinedby the measuring means.

[0046] In this aspect, the subject can learn a series of positionsand/or movements of the aid that cause pre-programmed control signals orsequences thereof to be supplied to the stimulating means.

[0047] In one embodiment, the walling aid can comprise a crutch orwalking sticks. Placement of the crutch or stick at a particular anglerelative to vertical or its movement in a particular way can bepre-programmed to cause stimulation of a lower limb in a manner thatallows the subject to walk. In a preferred embodiment, the system relieson at least one measuring means mounted on respective crutchessupporting the subject. A particular movement or position of the leftcrutch can be adapted to cause stimulation of the right leg. Asubsequent particular movement or position of the right crutch can beadapted to cause stimulation of the left leg. In this manner, a subjectcan learn to walk using the FES system by alternately moving oradjusting the position of the crutches used to support them. In analternative arrangement, it can be envisaged that the subject rely onone crutch or walking stick. In this case, variation in the positionand/or movement of the aid can lead to stimulation of the opposing leg.The adjacent leg can then be stimulated to take a stride 180° out ofphase of the opposing leg.

[0048] In this aspect, the monitoring means, control means andstimulating means can have the features of the equivalent systemsalready defined herein.

[0049] According to a still further aspect, the present invention is awalking aid for a subject being assisted to walk using functionalelectrical stimulation system, the walking aid having at least onesensor mounted thereon that outputs signals representative of theposition and/or movement of the walking aid.

[0050] In this aspect, the functional electrical stimulation system canhave the features of the FES system defined above.

[0051] In this aspect, the walking aid can comprise a crutch. The crutchcan comprise a tall crutch that fits under the armpits with doubleuprights and a small horizontal band bar extending between the uprights,a Lofstrand crutch which consists of a single tube of aluminiumsurrounded by a metal cuff that fits round the forearm and has a handbarpositioned proximally thereto, or a Canadian elbow extensor crutch whichis a variation of the Lofstrand crutch. Still further, the walking aidcan comprise a walked stick.

[0052] The walking aid can have an on-board power supply, such as arechargeable battery, that provides power to the sensor. In anotherembodiment, componentry of the FES system, such as the control means andstimulator can be mounted on or in the walking aid. Electricalconnectors can also be incorporated into the walking aid to allow cablesto extend from the componentry mounted to or in the walking aid to theone or more transducers and/or the stimulating electrodes.

[0053] According to a further aspect, the invention is a method ofcontrolling functional electrical stimulation provided to a portion of abody of a subject, the method comprising the steps of:

[0054] measuring the position and/or movement of a portion of the bodyof the subject other than said body portion; and

[0055] processing the signals and outputting electrically stimulation tosaid body portion in response to the measured position and/or movementof said other body portion.

[0056] In a preferred embodiment of this aspect, the method is adaptedto use the position and/or movement of the torso, the head, one or botharms, or a combination thereof, to control the stimulation provided tothe legs of the subject. In a particularly preferred embodiment, theposition and/or movement of the torso and/or head can be used toinitiate and control a standing or sitting action of the subject. Inanother embodiment, the movement of the torso and/or head can be used toinitiate stimulation of the legs that allows the subject to roll overwhen in a substantially horizontal position.

[0057] According to a still further aspect, the invention is a method ofcontrolling functional electrical stimulation provided to a port on of abody of a subject, the method comprising the steps of

[0058] measuring the position and/or movement of a walking aid operatedby the subject; and

[0059] processing the signals and outputting electrical stimulation tosaid body portion in response to the measured position and/or movementof said walking aid.

[0060] In a preferred embodiment of this aspect, the electricalstimulation is provided to the legs of the subject to cause the subjectto walk.

[0061] In a preferred embodiment of these latter aspects, the methodincludes a step of measuring the position and/or movement of the legsand using the measurements to modify or control the electricalstimulation generated in response to movement of the subjects torso orwalking aid.

BRIEF DESCRIPTION OF THE DRAWINGS

[0062] By way of example only, preferred embodiments of the inventionare now described with reference to the accompanying drawing, in which:

[0063]FIG. 1 is a sequence of drawings depicting the movement of asubject's body from a sitting position to a standing position usingfunctional electrical stimulation;

[0064]FIG. 2 is a sequence of drawings depicting the movement of asubject's body from as standing position to a sitting position usingfunctional electrical stimulation;

[0065]FIG. 3 is a side elevation view of one embodiment of a walking aidaccording to the present invention;

[0066]FIG. 4 is a sequence of drawings depicting the gait of a personusing walking aids in concert with a functional electrical stimulationsystem; and

[0067]FIG. 5 is a simplified block diagram depicting one embodiment of aFES system according to the present invention.

PREFERRED MODE OF CARVING OUT THE INVENTION

[0068] A FES system according to the present invention is generallydepicted as 30 in FIG. 5.

[0069] The system has a housing 31 that houses a control means 32 and astimulator 35. A power source in the form of a rechargeable battery 43is also provided in the housing 31. The depicted control means 32receives a first set of signals through a first signal path 33 providedby a cable 40 extending from a first transducer 60 to an electricalconnector 33 a on the housing 31. The transducer 60 and cable 40 aredepicted schematically in FIG. 5 and are not shown to scale. Thetransducer 60 is adapted to be mounted to a portion of the body of thesubject that is under the control of the subject. For example, in thecase of subject with paraplegia, the transducer can be mounted to theupper torso of the subject.

[0070] The signals output by transducer 60 and provided through signalpath 33 represent the magnitude and type of movement of the torso madeby the subject.

[0071] While the control means 32 could rely only on the input fromtransducer 60, the depicted control means 32 also receives a second setof output signals through a second signal path 34 provided by a cable 50extending from a transducer 61. Transducer 61 can also be mounted to thetorso of the subject or at another location on the subjects body. Whiledepicted schematically in FIG. 5, the cables 40,50 can be envisaged asbeing a flexible cables extending between the respective transducers60,61 and the connectors 33 a,34 a of the housing 31. The signals outputby transducer 61 and provided through signal path 34 can also representthe magnitude and type of movement made by the portion of the subject'sbody to which the transducer 61 is mounted.

[0072] In one arrangement the control means 32 receives the first set ofoutput signals through the first signal path 13 from transducer 60 whenmounted to the torso of the subject and the second set of output signalsthrough the second signal path 34 from transducer 61 mounted to one ofthe legs of the subject. While FIG. 5 depicts only one transducerproviding signals through each of the signal paths 33 and 34, more thanone transducer could be utilised to provide signals through each signalpath.

[0073] The transducer 60 mounted to the torso of the subject 12 providesa signal output representative of the angle of the torso relative to ahorizontal plane and the movement of the torso. The transducer 61mounted to one of the legs of the subject provides a signal outputrepresentative of the angle of the thigh of the leg relative to ahorizontal plane and the movement of the legs. When monitoring only oneleg, the control means 32 can be operated in a manner that assumes theother leg is in a position 180° out of phase to the monitored leg, whenthe subject is receiving functional electrical stimulation that resultsin the subject being able to walk or move their legs in some repetitivemanner, such as rotate the pedals of an exercise bicycle.

[0074]FIG. 1 depicts one use of one embodiment of the FES system 30depicted in FIG. 5. In FIG. 1, a simplified view of a subject 12receiving functional electrical stimulation is depicted. In FIG. 1a, thesubject 12 is shown seated on a chair 13. As shown in FIG. 1b, thesubject 12 can move their torso 14 forwardly to a position that is at aparticular angle relative to a horizontal plane. The transducer 60mounted to the torso 14 detects this movement and outputs signalsrepresentative of this to the control means 32. The control means 32 onreceipt of these signals in turn outputs suitable control signals to thestimulator 35 which outputs electrical impulses to electrodes 53 mountedto the legs 15 of the subject 12. For reasons of clarity, the system 30and electrodes 53 are not depicted in FIG. 1

[0075] As can be seen in FIG. 1b, as the subject 12 moves their torso 14forward, the lower legs of the subject 12 move backwardly. The angle ofthe torso 14 controls the angle of movement of the lower legs about theknees of the subject 12.

[0076] Once the feet of the subject 12 are in the correct position, thesubject 12 can return their torso 14 back to an upright position asdepicted in FIG. 1c. This movement leads to further signals being outputto the control means 32. Once the torso 14 is back in an uprightposition, the control means 32 can output control signals to thestimulator 15 which result in the stimulator 35 outputting a sequence ofstimulation impulses to the legs 15 that result in the subject 12 movingto a standing position (see FIGS. 1d and 1 e).

[0077]FIG. 2 depicts another use of an embodiment of the FES system 30.In these figures, the subject 12 is firstly shown standing in front of achair 13. On a subject 12 moving their torso 14 forward a particulardesired angle, such as greater than 30°, and then returning to anupright position within a predetermined time (see FIG. 2a), thetransducer 60 detects this combination of movements and outputsappropriate representative signals to the control means 32. The controlmeans 32 on receiving this combination of signals, outputs controlsignals to the stimulator 35 which results in the thighs of the subject12 bending backwardly relative to the knees (see FIG. 2b) so as to movethe subject 12 back down onto the chair 13 as depicted in FIG. 2c.

[0078]FIGS. 1 and 2 depict examples of how the FES system 30 can be usedby the subject 12 adjusting their torso to control the movement of theirdysfunctional legs.

[0079] The control means 32 is programmed to output a particularstimulation signal sequence to the stimulator 35 on detection of apredetermined torso position adopted by the subject 12. In this way, thesubject 12 can learn to create particular different stimulation patternsor signal sequences by the stimulator 35 by adopting various differenttorso positions.

[0080] While the use of torso orientation is depicted in FIGS. 1 and 2for initiating a standing up or sitting down action, torso orientationchanges can also be used to initiate and maintain a walling sequence. Inanother embodiment, the control means 32 can be adapted to watch fortwisting movements of the torso that are indicative, when the subject islaying down, that the subject wishes to roll over. The control means canalso include a timer means that ensures the subject 12 rolls over apredetermined number of times in a particular time period.

[0081] The transducer 61 mounted to the legs of the subject 12 can alsobe utilised as a means of feeding back information to the control means32 following electrical stimulation of the legs by the stimulator 35.For example, the transducer 61 can inform the control means 32 that thestimulator 35 has or has not achieved the outcome for the legs expectedby the provided stimulation.

[0082] The control means 32 can also control the stimulation applied bythe stimulator 35 based on a comparison of angles or orientation of thetorso relative to the upper and lower leg (knee) angle. As previouslymentioned, the detected torso angle relative to the horizontal plane canbe approximated to the desired knee angle such that the desired kneeangle can be considered as a function of the measured torso angle. Thecontrol means 32 can then initiate appropriate signals to ensure thatthe actual knee angle closely approximates that of the desired kneeangle based on a model of desired knee angles and torso angles.

[0083] The depicted control means 32 comprises a microprocessor andincludes a data storage buffer that stores measured torso movementsmeasured by the transducer 60 and/or leg movements resulting from theprovision of electrical stimulation thereto.

[0084] One embodiment of a crutch for use as a walking aid according tothe present invention is depicted generally as 20 in FIG. 3. Thedepicted crutch 20 comprises a standard tall crutch, however, thepresent invention could also equally rely on a Lofstrand crutch orCanadian elbow extensor crutch.

[0085] The crutch 20 has an armpit portion 21 and two double uprights 22that extend from the armpit portion 21 to a foot 23. A small horizontalhandbar 24 extends between the uprights 22 which allows the subject 12to use and support themselves on the crutch 20.

[0086] Mounted to the crutch 20 below the handbar 24 is a transducer 25.The transducer 25 can have the same or different features to that oftransducer 60 described above. Extending from the transducer is a cable26. In the depicted embodiment, cable 26 is adapted to be electricallyconnected to connector 33 a of the FES system 30. The transducer 25 isused to provide signals to the control means 32 in replacement of or inaddition to signals provided by transducer 60 mounted to the torso ofthe subject 12. By varying the position of one or two crutches beingused by the subject 12, the subject 12 can control the stimulationpattern output by the stimulator 35. In one example, forward movement ofthe left crutch can result in a forward step of the right leg of thesubject 12 and subsequent forward movement of the right crutch canresult in a forward step of the left leg of the subject 12. Further thecontrol means 32 of this embodiment can determine the distance betweenthe subject's leg and the associated crutch and cause the leg to bebrought towards the crutch when the distance exceeds a specific limit.By learning to appropriately move the supporting crutches, a subject 12can create a sequence of steps using the FES system 30.

[0087] While FIG. 3 only depicts the transducer 25 mounted to the crutch20, in another embodiment, the housing 31 could be mounted on the crutch20.

[0088]FIG. 4 depicts a subject 12 using a walking stick in each hand tocontrol the FES system 30 in a manner similar to that described forcrutch 20. Walking stick 27 a is in the right hand of the subject 12 andwalking stick 27 b in the left band. For the purposes of clarity, theleft leg, left arm and left walking stick 27 b of the subject 12 aredepicted in phantom in FIG. 4.

[0089] Each walking stick 27 a,27 b has a transducer 25 mounted thereon(not visible) that is used to provide signals to the control means 32 inreplacement of or in addition to signals provided by transducer 60mounted to the torso of the subject 12. By varying the position of thesticks 27 a,27 b, the subject 12 can control the stimulation patternoutput by the stimulator 35.

[0090] In one example, forward movement of the left stick 27 b canresult in a forward step of the right leg 15 a of the subject 12 andsubsequent forward movement of the right stick 27 a can result in aforward step of the left leg 15 b of the subject 12. As depicted in FIG.4b, the subject 12 has moved the left stick 27 b forward which in turnhas resulted in the subjects right leg 15 a stepping forward a distancesimilar to or the same as that moved by the left stick 27 b. Once thisstep is complete, the subject 12 can move the right stick 27 a forward(as depicted in FIG. 4c) which in turn leads the FES system 30 to movethe left leg 15 b forward a distance similar to or the same as thatmoved by the right stick 27 a. By continuously moving the sticks 27 a,27b forward in alternate fashion, the subject 12 can walk across asurface.

[0091] While the use of the sticks 27 a,27 b is depicted in FIG. 4 asresulting in a walking movement of the subject 12, it will beappreciated that other movements of one or both sticks can result inother movements of the subject 12. For example, the lifting of one ofthe sticks may cause the subject to sit or stand.

[0092] The components of the depicted FES system 30 can be fullyimplanted within the subject 12. It will, however, be appreciated thatthe control means 32 and other components could be external the body ofthe subject 12. Electrical stimulation to the muscles is provided, inthe depicted embodiment, by electrodes 53 mounted to the skin orimplanted within the muscles identified as requiring stimulation toachieve the movement desired when installing the system 30. As depictedin FIG. 5, the electrodes 53 are electrically connected by cables 54 tothe output of stimulator 35 through a connector 35 a on the housing 31.

[0093] As depicted in FIG. 5, the system 30 further comprises anoperating means 36 that receives signals from a transducer 37 adapted tomonitor the position of another portion of the subjects body, such asthe subject's head. The transducer 37 outputs signals through cable 38connected to connector 39 in the housing 31. The transducer 37 and cable38 are not depicted to scale. More than one such transducer 37 can alsobe envisaged. On receipt of a predetermined signal from the transducer37, the operating means can activate or deactivate the control means 32and/or the stimulator 35. For example, the transducer 37 can be mountedto the head of the person 12, and adapted to output a predeterminedsignal on determination of a particular movement of the person's headrelative to the their torso. This provides the person 12 with a readymeans to activate or deactivate the FES system 30 simply by apredetermined movement of their head. It can be envisaged that movementof the subject's torso 14 or the walking aid 20 held by the person 12could also be used to activate or deactivate the control means 32 and/orthe FES system 30.

[0094] The FES system 30 provides a relatively easier and more naturalinterface for the subject 12 to initiate a step or other movement whencompared to button presses using known touch pad interfaces.

[0095] It will be appreciated by persons skilled in the art thatnumerous variations and/or modifications may be made to the invention asshown in the specific embodiments without departing from the spirit orscope of the invention as broadly described. The present embodimentsare, therefore, to be considered in all respects as illustrative and notrestrictive.

1. A functional electrical stimulation system for controlling themovement of one or both legs of a body of a subject comprising: ameasuring means having at least one sensor that is mountable to thetorso, head and/or one of both arms of the subject and which outputssignals representative of the angle of said subject's torso head and/orone of both arms relative to a predetermined plane selected from thegroup comprising a sagittal plane, a frontal plane or a horizontalplane; and a control means that receives and processes the signalsoutput by the measuring means and outputs control signals to astimulating means adapted to provide electrical stimulation to said oneor both legs in response to the angle of the subject's torso, headand/or one or both arms determined by the measuring means.
 2. Afunctional electrical stimulation system of claim 1 wherein themeasuring means only measures the angle of the torso, head and/or one orboth arms when that body portion has stopped gross movement.
 3. Afunctional electrical stimulation system of claim 2 wherein on detectingtwisting movements of the torso and that the subject is at leastsubstantially horizontal, the control means outputs control signals thatcause the stimulating means to output a sequence of stimulation impulsesthat serve to roll the subject over.
 4. A functional electricalstimulation system of claim 1 wherein the measuring means comprises atleast one transducer.
 5. A functional electrical stimulation system ofclaim 4 wherein said at least one transducer is implantable within thesubject.
 6. A functional electrical stimulation system of claim 1wherein the control means further comprises a storage means having atleast one predetermined action sequence storable therein, and furtherwherein, on receipt of signals from the measuring means, said at leastone predetermined action sequence is provided to the stimulating means.7. A functional electrical stimulation system of claim 6 wherein said atleast one predetermined action sequence results in the subject movingfrom a standing to a sitting position, or moving from a sitting to astanding position, walking, or moving the legs in a pedalling action. 8.A functional electrical stimulation system of claim 1 wherein thecontrol means outputs control signals to the stimulating means when thetorso of the subject is bent forward by an angle of between about 10°and about 60°, more preferably between about 25° and about 50°, andstill more preferably between about 25° and about 45° relative to anotional horizontal plane.
 9. A functional electrical stimulation systemof claim 1 wherein the stimulating means comprises a stimulator and atleast one electrode mountable on said body portion and electricallyconnected to the output of the stimulator.
 10. A functional electricalstimulation system of claim 1 wherein the system further comprises anoverride means that monitors the position of said subject and preventsprovision of electrical stimulation to said body portion if the positionof said subject is such that stimulation is inappropriate or unsafe forthe subject.
 11. A functional electrical stimulation system of claim 3wherein the control means is programmed to output signals to thestimulating means to cause roll over of the subject at predeterminedtimes.
 12. A functional electrical stimulation system of claim 11wherein the control means is programmed to output signals causing rollover of the subject at least 2 times in an 8 hour period.
 13. Afunctional electrical stimulation system of claim 1 wherein the systemfurther comprises a feedback means that measures the position and/ormovement of said body portion being stimulated by the stimulating meansand provides output signals to the control means representative of thesemeasurements.
 14. A functional electrical stimulation system of claim 1wherein the control means has an operating means having an activationand deactivation means that allows the subject to turn on and off thecontrol means and/or the functional electrical stimulation system whendesired.
 15. A functional electrical stimulation system for controllingthe movement of a portion of a body of a subject comprising: a measuringmeans having at least one sensor that is mountable to the torso of thesubject and which outputs signals representative of the angle of saidsubject's torso relative to a predetermined plane selected from thegroup comprising a sagittal plane, a frontal plane or a horizontalplane; and a control means that receives and processes the signalsoutput by the measuring means and outputs control signals to astimulating means adapted to provide electrical stimulation to said oneor both legs in response to the angle of the subject's torso determinedby the measuring means; wherein on detecting twisting movements of thetorso and that the subject is at least substantially horizontal, thecontrol means outputs control signals that cause the stimulating meansto output a sequence of stimulation impulses that serve to roll thesubject over.
 16. A functional electrical stimulation system of claim 15wherein the control means is programmed to output signals to thestimulating means to cause roll over of the subject at predeterminedtimes.
 17. A functional electrical stimulation system of claim 16wherein the control means is programmed to output signals causing rollover of the subject at least 2 times in an 8 hour period.
 18. Afunctional electrical stimulation system for controlling the movement ofone or both legs of a body of a subject comprising: a measuring meanshaving at least one sensor that is mountable to the torso, head and/orone of both arms of the subject and which outputs signals representativeof the angle of said subject's torso, head and/or one of both armsrelative to a predetermined plane selected from the group comprising asagittal plane, a frontal plane or a horizontal plane; a control means;and a stimulating means; wherein the control means further comprises astorage means having at least one predetermined action sequence storabletherein that is provided to the stimulating means on receipt ofpredetermined control signals from the control means, said actionsequence resulting in the subject moving from a standing to a sittingposition or moving from a sitting to a standing position.
 19. A controlmeans for a functional electrical stimulation system that provides asubject that is unable to walk naturally with a means of continuouslycontrolling a walking sequence created by the functional electricalstimulation system during performance of the sequence, the functionalelectrical system comprising: a measuring means having at least onesensor which outputs signals representative of the current position andmovement of a portion of the subject's body that can be moved naturallyby the subject; a control means; and a stimulating means; wherein thecontrol means receives and processes signals output by the measuringmeans and outputs control signals to the stimulating means to provideelectrical stimulation suitable to cause the legs of the subject to movewith a walking movement, said movement being in response to the currentposition and movement of said body portion as determined by themeasuring means.
 20. A control means for a functional electricalstimulation system of claim 19 wherein sequential variation in torsoand/or head position as adopted by the subject is measurable by themeasuring means and results in the control means outputting a sequenceof control signals to the stimulating means that causes a sequence ofstep movements by the legs of the subject.
 21. A functional electricalstimulation system for controlling the movement of a portion of a bodyof a subject comprising: a measuring means having at least one sensor,mountable to a walking aid, that outputs signals representative of theposition and/or movement of said walking aid when operated by a subjectof the system; and a control means that receives and processes thesignals output by the measuring means and outputs control signals to astimulating means adapted to provide electrical stimulation to said bodyportion in response to the position and/or movement of said walking aiddetermined by the measuring means.
 22. A functional electricalstimulation system of claim 21 wherein the walking aid comprises acrutch or walking stick.
 23. A functional electrical stimulation systemof claim 22 wherein variation in movement and/or position of the crutchor stick causes stimulation of the legs of the subject in a manner thatallows the subject to walk.
 24. A functional electrical stimulationsystem of claim 23 wherein at least one measuring means is mounted onrespective crutches supporting the subject.
 25. A walking aid for use bya subject being assisted to walk using a functional electricalstimulation system, the walking aid having at least one sensor mountedthereon that outputs signals representative of the position and/ormovement of the walking aid.
 26. A walking aid of claim 25 wherein thefunctional electrical stimulation system is as defined in claim
 21. 27.A walking aid of claim 25 wherein the walking aid comprises a crutch.28. A walking aid of claim 27 wherein the crutch is selected from thegroup comprising a tall crutch, a Lofstrand crutch, and a Canadian elbowextensor crutch.
 29. A walking aid of claim 25 wherein the walking aidis a walking stick.
 30. A walking aid of claim 25 wherein the walkingaid has an on-board power supply that provides power for at least thesensor.
 31. A method of controlling functional electrical stimulationprovided to a one or both legs of a subject, the method comprising thesteps of: measuring the angle of said subject's torso, head and/or oneor both arms relative to a predetermined plane selected from the groupcomprising a sagittal plane, a frontal plane or a horizontal plane; andprocessing the signals; and outputting electrically stimulation to saidone or both legs in response to the measured position and/or movement ofsaid subject's torso, head and/or one or both arms.
 32. A method ofcontrolling functional electrical stimulation provided to a portion of abody of a subject, the method comprising the steps of measuring theposition and/or movement of a walking aid operated by the subject; andprocessing the signals; and outputting electrical stimulation to saidbody portion in response to the measured position and/or movement ofsaid walking aid.
 33. A method of controlling functional electricalstimulation provided to a portion of a body of a subject of claim 32wherein the electrical stimulation is provided to the legs of thesubject to cause the subject to walk.
 34. A method of controllingfunctional electrical stimulation provided to a portion of a body of asubject of claim 33 further comprising the step of measuring theposition and/or movement of the legs of the subject and using themeasurements to modify or control the electrical stimulation generatedin response to movement of the subject's walking aid.